1. Field of the Invention
The invention relates to a substrate composition comprising substrate material and material providing structure and shape arranged distributed in the substrate material.
2. Description of Related Art
Such a substrate composition is known from EP-A-0 249 261.
In this prior art substrate composition use is made of substrate material formed by fibres and the material providing structure and shape is formed by thermoplastic fibres.
This has the result that in order to form form-retaining units the substrate material must be subjected to a temperature treatment. This requires much energy. The form-retention of such a unit is moreover generally very mediocre; such a unit will already disintegrate when only a small force is applied. This makes mechanical handling of such units difficult.
The object of the present invention is to provide a substrate composition, wherein the above stated drawbacks are obviated.
This objective is achieved in that the particles are mutually connected by a binder.
As a result of this binder it is no longer necessary to perform a temperature treatment, so that the associated drawbacks are avoided. In addition, the form-retention of such a unit is considerably greater than of the prior art units.
The substrate material is preferably formed by potting compost or other organic material.
Particularly in recent years much resistance has arisen to the use of pure synthetic substrate substances, because it is assumed that these have an adverse effect on the flavour of the products cultivated on substrate manufactured from such material. There is therfore an increasing need for the use of substrate of organic origin.
Further known is the use of foam particles as material providing structure and shape in such prior art substrates. The foam particles have the function here of improving the water-absorbing properties of the substrate. The presence of such foam particles thus also makes it possible to apply the binder according to the present invention. The advantage of the present invention is herein combined with the advantage of applying foam particles.
It is pointed out here that the present invention is certainly not limited to the application of foam particles; the use of fibres is envisaged in the first instance.
A combination of both forms is of course also possible.
According to a preferred embodiment the fibres or foam particles are formed from a polymer.
The binder is preferably formed by a pre-polymer reacting with water.
This has the advantage that the polymerization takes place when water comes into contact with the binder. This takes place for instance when the binder is brought into contact with the potting compost.
The degree of integrity and strength of the units formed from the substrate composition can be determined by varying the quantity of fibres and the amount of binder.
Other attractive embodiments are stated in the remaining claims.